To be fair, this is under the assumption that the parks themselves know exactly what is and isn't opening. We know what the government is like for last-minute details - case in point, pubs being told today that they can't open until 6am tomorrow, with many having planned midnight openings*.
There's every possibility that things are still somewhat in flux, and could change.
(* - for the record, I think this was an insane idea for any pub to seriously consider, and very much against the spirit of the new regulations. But many had planned it)